Backup circuit for electricity supply, elevator system, and method

ABSTRACT

The invention relates to a backup circuit for electricity supply for ensuring the electricity supply of an electronic overspeed governor in connection with a malfunction of the electricity supply. The backup circuit for electricity supply comprises an energy storage. The backup circuit for electricity supply is configured to disconnect the electricity supply from the energy storage ensuring the electricity supply of the electronic overspeed governor to the overspeed governor when the malfunction of the electricity supply continues.

FIELD OF THE INVENTION

The invention relates to solutions for ensuring the electricity supplyof an electronic overspeed governor.

BACKGROUND OF THE INVENTION

An overspeed governor is normally used for monitoring unintendedmovement of an elevator car. The overspeed governor activates a safetygear preventing movement of the elevator car, if the speed grows of theelevator car becomes too high. The overspeed governor is connected tothe safety gear with a rope, which passes via the rope pulley of theoverspeed governor. The rope pulley of the overspeed governor isnormally able to rotate freely when the elevator car is moving. Theoverspeed governor activates the safety gear by stopping the movement ofthe rope of the safety gear. In practice, this occurs by locking themovement of the rope pulley of the overspeed governor with a lockingmeans of the rope pulley, if the speed of the elevator car becomes toohigh. The locking means shifts from a position permitting movement ofthe rope pulley into a position preventing movement of the rope pulleyfrom the effect of centrifugal force.

An electronic overspeed governor is also proposed for monitoringunintended movement of an elevator car. An electronic overspeed governorcomprises a microprocessor control, so that it enables more versatilemonitoring of the movement of an elevator car than before. A number ofvalues can be set for the limit value for the maximum permitted speed ofthe elevator car and the values can also be changed as a function of theposition of the elevator car e.g. such that the limit value for themaximum permitted speed decreases when the elevator car approaches theend of the elevator hoistway. Publication U.S. Pat. No. 6,170,614 B1presents the operating principle of one electronic overspeed governor.

Despite their obvious advantages electronic overspeed governors have notyet, however, displaced conventional mechanically-controlled overspeedgovernors to any significant extent in the safety arrangements ofelevators. Conventional mechanically-controlled overspeed governors haveretained their position owing to inter alia their simplicity,operational reliability and reliable structure.

An electronic overspeed governor also functions as an elevator safetydevice that is required by elevator regulations. For this reason anoverspeed governor must be designed to be fail-safe such that amalfunction in the overspeed governor, e.g. a disturbance of theelectricity supply of the overspeed governor, always results in thegripping of a moving elevator car.

One problem related to an electronic overspeed governor is how to ensurethe operation of the overspeed governor in connection with anelectricity outage. An elevator car must be able to be moved e.g. in anemergency braking situation and/or in an emergency rescue situationregardless of an electricity outage. Earlier this problem has beensolved by using an accumulator of sufficiently large charge capacity asa reserve power source of the overspeed governor, which accumulatorsupplies current to the overspeed governor during an electricity outage.A drawback in this solution is the unpredictability of the timing of theemergency rescue, especially if the electricity outage affects a largecity or large part of a city. If the accumulators have emptied there isnothing to indicate the operating condition of the electronic overspeedgovernor to the rescue personnel. In this case, when trying to move theelevator car by opening the machinery brakes the safety gear stops anymovement of the elevator car.

AIM OF THE INVENTION

One object of the invention is to disclose a more reliable solution thanprior art to the problem of ensuring the electricity supply of anelectronic overspeed governor in connection with a malfunction of theelectricity supply. To achieve this aim the invention discloses a backupcircuit for electricity supply according to claim 1, a backup circuitfor electricity supply according to claim 8, an elevator systemaccording to claim 9, and also a method according to claim 10. Thepreferred embodiments of the invention are described in the dependentclaims. Some inventive embodiments and inventive combinations of thevarious embodiments are also presented in the descriptive section and inthe drawings of the present application.

SUMMARY OF THE INVENTION

The backup circuit for electricity supply according to the invention forensuring the electricity supply of an electronic overspeed governor inconnection with a malfunction of the electricity supply comprises anenergy storage for supplying electricity to the overspeed governor. Thebackup circuit for electricity supply is configured to disconnect theelectricity supply from the energy storage ensuring the electricitysupply of the electronic overspeed governor to the overspeed governor upuntil the disconnection of the electricity supply while the malfunctionof the electricity supply continues. In a preferred embodiment of theinvention the overspeed governor is therefore preferably fail-safe sothat the overspeed governor is fitted to activate the gripping functionwhen the electricity supply to the overspeed governor is disturbed. In apreferred embodiment of the invention the backup circuit for electricitysupply is further configured to restart the electricity supply occurringfrom the energy storage to the overspeed governor when the malfunctionof the electricity supply continues. In a preferred embodiment of theinvention the backup circuit for electricity supply is configured tostart the electricity supply occurring from the energy storage to theoverspeed governor for the purpose of emergency drive of the elevator.The backup circuit for electricity supply preferably comprises acontrollable switch for disconnecting the electricity supply occurringfrom the energy storage to the overspeed governor and/or for restartingsaid electricity supply. The invention enables the preserving of thecharge of the energy storage that is in the backup circuit for theelectricity supply of an electronic overspeed governor during amalfunction of the electricity supply, almost irrespectively of theduration time of the malfunction.

In a preferred embodiment of the invention the backup circuit forelectricity supply is configured to disconnect the electricity supplyfrom the energy storage ensuring the electricity supply of theelectronic overspeed governor to the overspeed governor with a delaywhen a malfunction of the electricity supply is detected. Theaforementioned disconnection delay of the electricity supply ispreferably determined on the basis of the stopping delay of an apparatusmonitored by the overspeed governor, preferably on the basis of thestopping delay of the elevator car and/or of the counterweight. When theelectricity supply to the overspeed governor is disconnected only afterthe stopping of the elevator car /counterweight, the gripping of theelevator car/counterweight owing to disconnection of the electricitysupply of the overspeed governor can be prevented.

In one embodiment of the invention the backup circuit for electricitysupply is configured to receive a control signal for starting theelectricity supply occurring from the energy storage to the overspeedgovernor. In this case the electricity supply to the overspeed governorcan be started in a controlled manner e.g. in connection with a servicedrive procedure and/or an emergency drive procedure of the elevator. Inone embodiment of the invention a control signal for starting theelectricity supply occurring from the energy storage to the overspeedgovernor is sent from the emergency drive unit of the elevator to theoverspeed governor. In one embodiment of the invention a control signalfor starting the electricity supply occurring from the energy storage tothe overspeed governor is sent from the service center for the elevatorsto the overspeed governor; in this case the aforementioned emergencydrive/servicing procedure requiring the starting of the electricitysupply of the overspeed governor can also be started and/or executed byremote control from the service center.

The invention also relates to a backup circuit for electricity supplyfor ensuring the electricity supply of an electronic overspeed governorin connection with a malfunction of the electricity supply, which backupcircuit for electricity supply comprises an energy storage, and whichbackup circuit for electricity supply is provided with signaling meansfor indicating the state of charge of the aforementioned energy storage.In this case the rescue personnel are able, by means of the signalingmeans, to ascertain the state of charge of the energy storage before theelevator car is moved, in which case it is not futilely endeavored tomove the elevator car before there is sufficient charge in the energystorage to prevent gripping of the elevator car in connection with arescue procedure.

The elevator system according to the invention comprises an electronicoverspeed governor for preventing unintended movement of an elevator carand/or of a counterweight. The elevator system comprises a backupcircuit for electricity supply, according to any of those presented inthe preceding, for ensuring the electricity supply of an overspeedgovernor in connection with a malfunction of the electricity supply ofthe elevator system. The invention is suited to elevator systems withcounterweights and to elevator systems without counterweights, saidelevator systems being intended e.g. for the transportation ofpassengers and/or freight.

In the method according to the invention for ensuring the electricitysupply of an electronic overspeed governor, electricity is supplied froman energy storage to the electronic overspeed governor in connectionwith a malfunction of the electricity supply, and also the electricitysupply from the energy storage ensuring the electricity supply of theelectronic overspeed governor to the overspeed governor is disconnectedwhile the malfunction of the electricity supply continues. In apreferred embodiment of the invention the electricity supply occurringfrom the energy storage to the overspeed governor is further re-startedwhen the malfunction of the electricity supply continues.

Taking into account what is presented above, the invention also relatesto an electronic overspeed governor, which comprises an interface to anenergy storage for ensuring the electricity supply of an overspeedgovernor. The electronic overspeed governor is configured to disconnectthe electricity supply from the energy storage ensuring the electricitysupply of the electronic overspeed governor (3) to the overspeedgovernor up until the disconnection of the electricity supply while themalfunction of the electricity supply continues. The overspeed governoris preferably fitted to activate the gripping function when theelectricity supply to the overspeed governor is disturbed.

The invention enables using an energy storage that is smaller in termsof its charge capacity than prior art for ensuring the electricitysupply of an electronic overspeed governor e.g. in an elevator system.In this case the energy storage used, such as an accumulator, can alsobe smaller in size than prior art. According to the invention the backupcircuit for the electricity supply of an electronic overspeed governoris also to a large extent independent of the duration of a malfunctionof the electricity supply, which is important especially in the types ofcases in which the time of servicing/rescue of the elevator is not knownexactly and in which an electricity outage might also last a long time.

At the same time the invention also enables improvement of thereliability of servicing/rescue activities during a malfunction of theelectricity supply and the fastest possible and trouble-free performanceof servicing/rescue activities.

The aforementioned summary, as well as the additional features andadvantages of the invention presented below, will be better understoodby the aid of the following description of some embodiments, saiddescription not limiting the scope of application of the invention.

BRIEF EXPLANATION OF THE FIGURES

In the following, the invention will be described in more detail by theaid of a few examples of its embodiments with reference to the attacheddrawings, wherein

FIG. 1 presents as a block diagram an elevator system according to theinvention

FIG. 2 illustrates the operation of an overspeed governor according tothe invention

FIG. 3 presents as a circuit diagram a backup circuit for electricitysupply according to the invention

FIG. 4 illustrates the determination of the disconnection delay for theelectricity supply of the overspeed governor in one embodiment of theinvention

MORE DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 presents as a block diagram an elevator system, in which theelevator car 5 and the counterweight 6 are suspended in the elevatorhoistway 13 with elevator ropes, a belt or corresponding passing via thetraction sheave of the hoisting machine 14. The torque thatmoves/supports the elevator car 5 is produced with the permanent-magnetsynchronous motor of the hoisting machine 1. The power supply to thepermanent-magnet synchronous motor occurs during normal operation froman electricity network 15 with a frequency converter 16. Current issupplied from the electricity network 15 also to otherelectrical/electronic devices of the elevator, when the electricitynetwork 15 is in operating condition.

The elevator system of FIG. 1 comprises as a safety device a safety gear17 of the elevator car, with which safety gear movement of the elevatorcar 5 is stopped in a dangerous situation, such as owing to adequatelylarge overspeed of the elevator car 5, by gripping to the guide rail(not shown) of the elevator car. In one embodiment of the invention theelevator system comprises as a safety device also a safety gear of thecounterweight, with which safety gear movement of the counterweight 6 isstopped in a dangerous situation by gripping to the guide rail (notshown) of the counterweight. One operating principle of a possiblesafety gear 17 of an elevator car also suited to the elevator system ofFIG. 1 is illustrated in FIG. 2. The frame part 18 of the safety gear 17is fixed in connection with the elevator car 5 such that the frame part18 moves along with the elevator car 5. The frame part 18 comprises ahousing 19, which contains a braking surface 21 towards the elevatorguide rail 20, and inside which housing 19 the elevator guide rail 20 isdisposed. Likewise, the housing 19 comprises a roller 22, which when thesafety gear 17 operates meets the elevator guide rail 20 and is disposedon a track 23 in the housing 19. The elevator guide rail 20 is betweenthe braking surface 21 and the roller 22. The track 23 is shaped suchthat when the roller 22 moves on the track 23 in the direction of theguide rail 20, the guide rail 20 presses against the braking surface 21under the effect of the roller 22 producing braking (gripping), whichstops the elevator car 5. For example, the gripping of an elevator car 5moving downwards in the direction of the arrow as presented in FIG. 2starts when the transmission means 25 that is in connection with therope pulley 11 of the overspeed governor of the elevator via the ropes24 pulls the roller 22 along the track 23 upwards to grip the guide rail20. In practice this occurs by locking the movement of the rope pulley11 when the elevator car 5 moves downwards, in which case the movementof the roller 22 decelerates with respect to the track 23 moving alongwith the elevator car and the roller 22 moves along the track 23 intothe gripping position.

An overspeed governor 3 measures the speed of the elevator car e.g. withan encoder fitted to the rope pulley 11 of the overspeed governor.

An electronic overspeed governor 3 activates the safety gear 17 bylocking the movement of the rope pulley 11 of the overspeed governorwith a solenoid 10. The solenoid 10 is movably supported on a frame part26, and the frame part 26 is attached to a stationary part of theoverspeed governor 3, so that movement of the rope pulley 11 isprevented by allowing the solenoid 10 to press onto the rope pulley 11.The solenoid comprises pushing means, such as pusher springs, whichpress the solenoid against the rope pulley 11. Detaching the solenoid 10from the rope pulley 11, and keeping it detached from the rope pulley,requires that current is supplied to the coil 9 of the electromagnet ofthe solenoid, which current brings about an attractive force opposingthe pushing force of the pushing means. An overspeed governor 3 istherefore fitted to activate the gripping function always when thecurrent supply to the coil 9 of the electromagnet of the solenoid isdisconnected. An overspeed governor 3 has been designed to be fail-safesuch that the current supply to the coil 9 of the electromagnet of thesolenoid disconnects and a moving elevator car 5 grips always inconnection with a malfunction of the overspeed governor 3, e.g. when theelectricity supply to the overspeed governor 3 malfunctions/disconnects.

Since an elevator car must be able to be moved also in connection withan electricity outage—e.g. in an emergency braking situation and/or inan emergency rescue situation—the electricity supply of the overspeedgovernor must be ensured e.g. with an accumulator or corresponding. Aproblem is that the accumulator capacity needed, and therefore the sizeof the accumulator for the overspeed governor 3, may increase to bequite large. For this reason the electricity supply of the overspeedgovernor 3 in the embodiment of the invention according to FIG. 2 isensured with a backup circuit 1 for electricity supply. The backupcircuit 1 for electricity supply supplies electricity to the overspeedgovernor 3 e.g. during a malfunction of the electricity network15/electricity outage. FIG. 3 presents in more detail a wiring diagramof a possible backup circuit for electricity supply suited e.g. to theembodiment of FIG. 2. In FIG. 3 the backup circuit 1 for electricitysupply comprises an accumulator 3, e.g. a lead accumulator, anickel-cadmium accumulator, a nickel-metal-hydride accumulator, alithium-ion accumulator or a lithium-polymer accumulator. The positivevoltage pole of the accumulator is connected to the positive supply pole27 of the electronic overspeed governor 3 with a switch 7. The switch 7is preferably a mechanical switch, such as a relay, but the use of asolid-state switch is also possible. The control of the switch 7 isarranged such that the switch opens and the electricity supply from theaccumulator 2 to the overspeed governor 3 disconnects if a malfunctionof the electricity network 15, such as electricity outage or a voltagereduction of the electricity network continues for a sufficiently longtime. For this reason the backup circuit 1 for electricity supplycomprises a releasing delay circuit 8, which forms a control signal foropening the switch 7 with a delay from the detected starting moment ofthe malfunction of the electricity network 15. In a preferred embodimentof the invention the switch 7 is a relay, the contact of which openswhen the current supply to the control coil of the relay 7 disconnects,in which case the releasing delay circuit 8 disconnects the currentsupply to the control coil of the relay with a delay from the start of amalfunction of the electricity network 15. The control logic of thereleasing delay circuit 8 can also be implemented by means of a program,e.g. in the software of the microprocessor of the overspeed governor 3.The aforementioned disconnection delay of the current supply is selectedtaking into account the movement of the elevator car in an emergencystop situation of the elevator. To illustrate this, FIG. 4 presents anemergency stop situation of an elevator, in which the machinery brakesof the hoisting machine of the elevator are activated to brake themovement of the traction sheave of the hoisting machine after a certainapparatus-dependent delay (e.g. approx. 100-500 milliseconds or more)from the start of a malfunction of the electricity network 15. When themachinery brakes are activated the speed v of the elevator car 5 startsto decelerate from its rated value, until the elevator car finallystops. The electronic overspeed governor 3 starts gripping of theelevator car 5 if the electricity supply to the electronic overspeedgovernor 3 disconnects when the elevator car 5 is still moving. For thisreason the opening of the contact of the relay 7 is delayed with a timedelay 4 such that the elevator car 5 has had time to stop before thecontact of the relay 7 opens.

After the contact of the relay 7 has opened, the electricity supply fromthe accumulator 2 to the overspeed governor 3 is prevented while amalfunction of the electricity network 15 continues. In certain specialsituations the electricity supply occurring from the accumulator 2 tothe overspeed governor 3 is re-started despite continuation of amalfunction of the electricity network 15, e.g. for transferringpassengers remaining in the elevator car 5 to the nearest possiblestopping floor of the elevator, either with emergency drive or,utilizing the force of gravity, by opening the machinery brakes of thehoisting machine. In one embodiment of the invention, more particularlyin connection with an elevator system without machine room, theelectricity supply from the accumulator 2 to the overspeed governor 3starts when the cover of the emergency drive unit of the elevator isopened. In elevator systems without machine rooms the emergency driveunit is generally disposed in connection with an entrance to theelevator hoistway, but it can also be disposed in a machine room. Theemergency drive unit is normally locked and it is opened only for thepurpose of emergency drive, installation, maintenance, or other suchspecial use of the elevator. The contact of the relay 7 of the backupcircuit 1 for electricity supply is configured to close when opening thecover of the emergency drive unit of the elevator. Closing of thecontact of the relay 7 can be implemented with positive closing e.g.such that the contact of the relay 7 is pressed closed e.g. from theeffect of a spring when opening the cover of the emergency drive unit.

In one embodiment of the invention, more particularly in connection withan elevator system without machine room, the contact of the relay 7disconnecting the electricity supply of the electronic overspeedgovernor 3 closes with positive closing by using a pushbutton in themachine room. The aforementioned pushbutton can be disposed e.g. in theemergency drive unit or elsewhere in the elevator control unit.

In a preferred embodiment of the invention the overspeed governor 3forms a status signal, which indicates the operating condition, moreparticularly the state of charge of the accumulator 2, of the overspeedgovernor 3. The emergency drive unit/another elevator control unitcomprises a signaling device, e.g. a green LED, which is controlled onthe basis of the status signal of the overspeed governor 3. In this casethe illumination of the green LED tells service personnel/rescuepersonnel that the accumulator 2 contains sufficient charge fordetaching the solenoid 10 of the overspeed governor from the rope pulley11, in which case the overspeed governor is operational and moving ofthe elevator car is possible in connection with a rescue procedure.

In the invention the term emergency braking situation refers to thestopping of the elevator car 5 by activating the machinery brakes of thehoisting machine 14 as well as by disconnecting the electricity supplyto the elevator motor.

The invention is described above by the aid of a few examples of itsembodiment. It is obvious to the person skilled in the art that theinvention is not only limited to the embodiments described above, butthat many other applications are possible within the scope of theinventive concept defined by the claims.

1. Backup circuit for electricity supply for ensuring the electricitysupply of an electronic overspeed governor [[(3)]] in connection with amalfunction of the electricity supply; which backup circuit forelectricity supply comprises an energy storage; wherein the backupcircuit for electricity supply is configured to disconnect theelectricity supply from the energy storage ensuring the electricitysupply of the electronic overspeed governor to the overspeed governorwhile the malfunction of the electricity supply continues.
 2. Backupcircuit for electricity supply according to claim 1, wherein the backupcircuit for electricity supply is configured to disconnect theelectricity supply from the energy storage ensuring the electricitysupply of the electronic overspeed governor to the overspeed governorwith a delay when a malfunction of the electricity supply is detected.3. Backup circuit for electricity supply according to claim 2, whereinthe disconnection delay for the electricity supply of the overspeedgovernor is determined on the basis of the stopping delay of theapparatus monitored by the overspeed governor.
 4. Backup circuit forelectricity supply according to any of the preceding claims, wherein thebackup circuit for electricity supply is configured to re-start theelectricity supply occurring from the energy storage to the overspeedgovernor when the malfunction of the electricity supply continues. 5.Backup circuit for electricity supply according to claim 4, wherein thebackup circuit for electricity supply is configured to start theelectricity supply occurring from the energy storage to the overspeedgovernor for the purpose of emergency drive of the elevator.
 6. Backupcircuit for electricity supply according to claim 1, wherein the backupcircuit for electricity supply is configured to receive a control signalfor starting the electricity supply occurring from the energy storage tothe overspeed governor.
 7. Backup circuit for electricity supplyaccording to claim 1, wherein the overspeed governor is fitted toactivate the gripping function when the electricity supply to theoverspeed governor is disturbed.
 8. Backup circuit for electricitysupply for ensuring the electricity supply of an electronic overspeedgovernor in connection with a malfunction of the electricity supply;which backup circuit for electricity supply comprises an energy storage;wherein the backup circuit for electricity supply is provided withsignaling means for indicating the state of charge of the energystorage.
 9. Elevator system, which comprises an electronic overspeedgovernor for preventing unintended movement of an elevator car and/or ofa counterweight, wherein the elevator system comprises a backup circuitfor electricity supply, according to claim 1, for ensuring theelectricity supply of an overspeed governor in connection with amalfunction of the electricity supply of the elevator system.
 10. Methodfor ensuring the electricity supply of an electronic overspeed governor,in which method electricity is supplied from an energy storage to theelectronic overspeed governor in connection with a malfunction of theelectricity supply, wherein the electricity supply from the energystorage ensuring the electricity supply of the electronic overspeedgovernor to the overspeed governor is disconnected while the malfunctionof the electricity supply continues.
 11. Method according to claim 10,wherein: the electricity supply occurring from the energy storage to theoverspeed governor is re-started when the malfunction of the electricitysupply continues.